Tuesday, 13 November 2018 20:21

Zenith's 1921 Patent on a Winding/Setting Stem

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I love this 1921 patent granted to Zenith for a couple of reasons.

First, the drawings are just a wonderfully straightforward depiction of a stem and crown that could be used for setting the hands (pushed in) or winding (pulled out). Second, it's always interesting to see an early version of something that's become such an integral part of watches today, and mores to see it in a slightly different light.

In the drawing above you can see the stem in the winding position, meshing with the top gear which would go to the power train. When pushed in, another set of gears on the stem mesh the hand setting mechanism. The leaf shapes help hold the gears together, and maintain the stem in a particular position. 

Wednesday, 07 November 2018 18:01

Tudor's Two-Way Adjustable Bracelet

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In this 2013 patent, Tudor discloses a fine adjustable watch bracelet that has both fine adjustment and elastic adjustment capabilities. While I try not to get too judgmental about these patents, I'm very surprised that this was issued.

The patent discloses two ways to adjust the fit of a bracelet, each at opposite ends of a wristband or clasp. 

The first is to attach springs in the bracelet. The springs allow the bracelet to stretch and return to its original position. This is something that was well-known in the art. 

The second is a series of grooves in the clasp, along with a bar which snaps into the grooves, also well-known in the art of fine-adjustment of bracelets. 

It's axiomatic that you can't combine two things, get the expected result, and obtain a patent on that. If already erasers existed, and pencils already existed, you usually can't get a patent on sticking an erase on a pencil. Here, I'm struggling to see what the point of novelty was, other than maybe the adjustments being at opposite ends of the clasp.

Regardless, it's an interesting, if not likely redundant, mechanism, that I don't believe we've seen in Tudors. 

Thursday, 01 November 2018 20:58

Hamilton's 1930s Antimagnetic Escape Wheel

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This is a patent that's very interesting for its historical context, and how clear the specification is about the problem it seeks to solve and how it solves it. This was filed in 1929 and issued in 1933 (don't let anyone tell you that long delays in getting a patent are a new thing).

The patent specification succinctly sums up what the problem was in the prior art, "As is well-known, a watch mechanism, or movement, containing parts of magnetic material, or which are sensitive to magnetism, or a magnetic field to which the movement is exposed, may have its accuracy impaired, or indeed under some conditions, its running may be stopped."

Steel was commonly used in the escape wheel to withstand the repeated hits from the pallet fork (pictured above) which may hit the escape wheel teeth three or more times a second. But steel wheels could easily be magnetized, and was susceptible to magnets. 

The most common anti-magnetic metal for use in gears was brass, but, "it is not hard enough to resist wear so that while its use for an escape wheel would eliminate the effect of magnetic influences, it would fail for want of wear resisting properties."

So, the inventor came up with a rather elegant solution. "I construct the escape wheel so that it has a main or body part of wheel-form, that is to say, a hub, spokes and rim or circumference, of a non-magnetic material, such as brass, and teeth of steel." There is a small enough amount of steel that it is largely unaffected by magnets, and the brass is just immune to its effects. Further, the combination of the metals, and their different coefficients of expansion as they heat are counteracted by the movement in the plates on which they are mounted.



Tuesday, 23 October 2018 20:55

Gruen's Day-Date Complication

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This Gruen Patent from 1972 is featured not because it's particularly groundbreaking, but because it does such a great job at showing one common way to implement day-date mechanisms. 

The day indicator is linked to the seven-sided star gear shown in the center, and it's advanced by the wheel to its left with a single finger. That wheel rotates once a day, and once a day rotates the star gear by 1/7th of a rotation, advancing a day wheel that shows the day of the week on the face of the watch.

Meanwhile in this implementation, the finger in the lower left will connect with the spurs on the date wheel around the edge. As it completes its rotation, it will advance the date wheel just like the date wheel does.

This particular implementation has a couple of interesting tweaks. The date cam is in a groove, so as it rotates around it also extends out a bit to better engage the spur. It also keeps the two wheels (day star wheel, and date wheel) in place with springs, that aid in limiting the movement to once a day when engaged by their respective cams.

Thursday, 18 October 2018 16:37

Chopard's Clever Balance Wheel Adjustment

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In 2003, Chopard was granted a patent on a clever system for adjusting a balance wheel on a watch. 

The most common ways of adjusting a balance wheel are a bit clunky. There are weights held on by pins. Screws that can be moved in and out, or removed entirely. Monochrome has a great article about this. All of these are to adjust the balance wheel's moment of inertia.

Think of the balance wheel like a figure skater. The skater takes a big push off, and starts spinning. At this point, the skater has some energy in the spin that is not going to increase. But, if the skater brings their arms closer to their body, they will spin faster. That's because by doing this they are reducing their moment of inertia - the energy it takes to spin - and spinner faster with the same amount of energy in the spin.

Similarly, the balance wheel is always getting a set amount of energy from the watch's power train. So to adjust its oscillation, you need to vary the balance wheel's moment of inertia. 

Enter the Chopard patent. It discloses small u-shaped weights that slot into holes in the outer rim of the balance wheel. By turning the weight at particular angles, you can adjust whether there is more weight toward the outside of the balance wheel (extending the skater's arms and increasing the moment of inertia) or closer to the center of the balance wheel (bringing the skater's arms in).

In a seeming rare case for this site, we can actually see that this patent is in use in a current Chopard watch.

Wednesday, 10 October 2018 21:32

ETA's Crown Function Display

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This is one of those patent's that is so simple and obvious that I was a little surprised not to have seen it before. I think this could be useful on watches with a million little complications, but then the question becomes where do you put the function indicator?

In this patent, the crown is connected to an indicator dial on the face of the watch. When the crown is pulled out to its first position, a finger engaged with the sleeve of the crown pulls a rack attached to the function dial. This rack and pinion connects the function dial on the face to the crown. 

One thing this doesn't account for is indicating how to turn the crown to adjust it when a given position on the crown controls two functions on the watch. I admit that every time I grab a day-date or a GMT watch with a date function I almost always rotate the crown the wrong way to adjust it first. As a result, my GMT watches are perpetually on some random timezone that I don't care a wick about.

Monday, 08 October 2018 22:44

Certina's 1971 Patent For Adjusting a Sealed Watch

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In the 1970s, Certina had a problem. There were already watches that were sealed and at low pressure to minimize oxidation of the gears and lubricating oils, but they were less accurate than other watches. Moreover, they were impossible to adjust while they were still sealed. 

So, Certina sought a way to adjust a fully sealed watch. And this is what they came up with. 

Certina put two bimetallic strips on either side of a regulation point, when heated, the bi-metaltic strips would push on the regulation point, adjusting the speed of oscillation. 

You may be familiar with bimetallic strips from older-style thermostats. They are exactly what they sound like. A strip of two metals, joined together. Because they are not the same, the metals expand differently when heat is applied, and the metal curves. For a thermostat, it typically has a mercury switch on one side, so when it bends too much in one direction (or unbends) it will turn the heater on or off.

Similarly here, these two bimetallic strips are able to be heated from the outside of the case, and then bend to adjust the oscillation of the movement and make a more accurate timekeeping device.

Tuesday, 02 October 2018 00:52

Breguet's North-South Moon Phase

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You probably don't think too often that you need slightly different moon phase mechanisms for a watch in the northern hemisphere compared to the southern. In fact, all you need is for the moon phase wheel, the wheel that has the moon on it, to rotate in the opposite direction: right to left on most watches.

In most watches, this would just be a matter of adding a gear, or assembling the mechanism differently. But what, Breguet asks, what do you do for someone who travels from the northern hemisphere to the southern, or vice versa?

Well, for that world traveler, who only wants to bring one watch with them, Breguet has an answer: a moon phase mechanism with counterrotating wheels, two heart cams, and a selection mechanism to engage one or the other. 

This is an interesting patent in that it may do fewer new things than any other modern patent we've featured here. It's basically two moon phases, with a selector between them. The heart cams allow the selection lever to engage one wheel or the other.

Like many of the patents here, this one is unlikely to see manufacture. It's not a really meaningful improvement on the existing mechanisms, and has incredibly limited real world use. 

Tuesday, 25 September 2018 22:09

Blancpain's Adjustable Snooze

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This is a delightfully over the top patent. Granted in December, 2017, this patent describes an adjustable mechanical snooze function on a watch with an alarm.

I say this is over the top because watches with alarms are rare enough. It seems unlikely that anyone would actually manufacture one with a snooze feature (prove me wrong if they exist already), let alone an adjustable snooze.

The mechanism by which the snooze is achieved is pretty straight froward. There's a rack and cam (pictured above). The angle of the rack determines the duration of the snooze, and the cam has multiple points where it can set the angle of the cam. 

This is really one of those patents that would make an absurdly high-end watch. Would I use this if I had it on a watch? Of course I would. Would I ever buy one? I cannot imagine a world where I would.

Wednesday, 12 September 2018 19:47

Audemars Piguet More Accurate Moon Phase

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Here's the thing with moon phase complications: they're popular, they're mechanically simple, and they're very bad at accurately displaying anything other than full and crescent moons.

The way most work is to have a semicircular opening with a smaller semicircle, or occulation disk on either end of the semicircle. As the moon emerges over left side, it starts as a tight crescent, and slowly grows to a full moon, before waxing. But the middle areas between the full moon and crescents are poor representations of the moon. If you check your moon phase at a half moon, it will look like a moon cookie with a bite taken out of it more than a half moon.

Enter Audemars. Their stated goal with this patent was to create a complication that did not add substantially to the complexity of the movement, while providing a more accurate representation of the moon at any given phase. What they've come up with is a really clever mechanism that was patented in the United States on July 30, 2013.

They maintain a few staples of more common moon phase complications. As shown in the patent, it keeps the semicircular opening for the complication, a moon disk with two moons opposed at 180 degrees from one another, and the traditional rotation rate of 29.5 days per half-turn. That is where the similarities end.

Instead of having semicircular occulation disks, the patented complication has two rotatable occulation disks that look vaguely like those three winged boomerangs. The disks can be calibrated to provide more accurate occulation of the moon at particular parts of its orbit. As the moon disk rotates it engages gears that move the occulation disks, typically in one quick movement, like with a date change.

In the end, this is a very interesting, but very high end complication. It adds a lot of pieces to what is typically a simple and inexpensive addition to a watch. I would really love to see this make its way into a watch, either by AP or licensed by someone else.

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